This application claims the priority of German patent document 100 01 783.5, filed Jan. 18, 2000, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a method of aligning an ACC-sensor (Adaptive Cruise Control Sensor) on a vehicle.
An ACC-sensor is a sensor which detects objects in the forward-moving range of a vehicle by emitting and receiving rays. Such sensors permit automatic vehicle control devices, for example, to maintain a particular distance from a vehicle driving ahead or to carry out a certain action when an obstacle suddenly appears in front of a vehicle. Such ACC-sensors operate, for example, on a laser, microwave or ultrasound basis.
To ensure accurate operation, such an ACC-sensor must be aligned correctly relative to the longitudinal direction of the vehicle itself, because a faulty alignment can lead to a malfunction of a corresponding control system.
German Patent Document DE 197 07 590 A1 discloses a method and apparatus for adjusting a distance sensor. In one embodiment, a reflector unit at a distance in front of the vehicle is aligned with respect to its body. A servicing unit then aligns the distance sensor based on the reflected rays. However, because the alignment of the reflector unit is performed with respect to the vehicle body, faulty adjustments may occur.
It is an object of the present invention, to provide a method of aligning an ACC-sensor on a vehicle which minimizes alignment errors.
This and other objects and advantages are achieved by the alignment method according to the invention, in which a reflection surface, such as a mirror, is used which reflects the rays emanating from the ACC-sensor onto a receiver situated in the ACC-device. When the reflection surface is aligned accurately, the ACC-sensor can be properly set up by adjusting it so that a defined or maximal fraction of the emitted radiation is reflected.
A main problem addressed by the invention therefore consists of accurately aligning the reflection surface. This is accomplished by aligning the horizontal axis of the reflection surface in parallel with the rear axle of the vehicle. The vertical axis of the reflection surface is aligned essentially perpendicular to the longitudinal axis of the vehicle, which is defined by the alignment of the front and rear axles.
As a result of the invention, faulty adjustments are prevented during the alignment of the ACC-sensor. The invention thus provides a significant advantage over prior alignment systems, in which the ACC-sensor is aligned according to the body of a vehicle as described previously. Such systems do not ensure that the ACC-sensor is actually aligned in the longitudinal direction of the vehicle, because the latter direction is defined not by the vehicle body, but by the position of the rear axle of the vehicle. In addition, the mutual orientation of the front and rear axles of the vehicle must also be taken into account for a vertical alignment, in order to ensure that the sensor will not emit its radiation too far downward or upward.
According to a preferred embodiment of the invention, on both sides of the vehicle the distance between the rear axle and the horizontal axis of the reflection surface is set to be identical. For this purpose, a measuring instrument, particularly a measuring tape, can be used, by means of which markings are made on both sides of the vehicle. The reflection surface can now be adjusted with respect to these markings. This takes place, for example, by using a laser pointer which is disposed relative to the reflection surface such that its laser beam extends parallel to the horizontal axis of the mirror. When the laser beam is then directed toward the markings, a parallel alignment of the horizontal axis of the reflection surface is ensured with respect to the rear axle of the vehicle.
For the essentially perpendicular alignment of the vertical axis of the reflection surface with respect to the longitudinal axis of the vehicle, the alignment of the longitudinal axis of the vehicle can be determined, for example, by means of a laser pointer which has a leveling device. The leveling device will then indicate the angle formed by a straight line that connects the two axles relative to the horizontal line. If the reflection surface is now set up such that its vertical axis is situated to be rotated by 90 degrees with respect to the defined angle, a proper vertical alignment of the reflection surface is achieved.
The present invention provides a simple and cost-effective possibility for aligning an ACC-sensor in the case of a vehicle.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.